Field effect transistors (FETs) are a type of transistor that relies on an electric field to control the conductivity of a channel of one type of charge carrier in a semiconductor material. FETs are sometimes called unipolar transistors to contrast their single-carrier-type operation with the dual-carrier-type operation of bipolar (junction) transistors (BJT).
Attempts to scale FETS (e.g., to the 45 nm to 28 nm nodes) are pushing the boundaries of current technology, resulting in diminishing returns. For example, as the FET is scaled, many limitations have been discovered. Specifically, it has been found that as the channel length L decreases, there is a considerable problem with a diminishing VT. This impairs device performance and makes it difficult to design integrated circuits with short channel lengths. It has also been found that attempts to further scale the FET (e.g., 45 nm to 28 nm nodes) has resulted in scattering and reduced electron mobility (short channel effects). This is due to a charge entering the substrate from an overlying dielectric layer.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.